Homework Help:
Unbanked circular motion

1. The problem statement, all variables and given/known data
a highway curve has a radius of 122m. At what angle should the road be banked so that a car travellin at 26.8m/s (60mph) has no tendency to skid sideways on the road? (frictional force is zero)

To start of you want to draw the setup as a force diagram at an arbitrary angle (called [itex]\theta[/itex] say), with:
- The normal reaction
- The centrifugal force from acceleration in a circle
- The Weight of the car

You need to find the angle at which all these forces are balanced. Does this help?